Structure and Function of Testis with Diagram and Spermatogenesis Explained
Testis, the plural is testes and it is the organ in the animal which produces the sperm, the male reproductive cell, and androgen is the male hormone. In humans, testes are oval-shaped organs that occur in the pair. Testes are present within the scrotal sac, and it is located directly behind the penis and in front of the anus. Testicles means the same as testes.
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Anatomy of the Testes
The physical property of each normal testis weighs about 25 grams which is equal to 0.875 ounces, four to five centimetre long (that is 1.6 - 2.0 inches), and two to three centimetre in diameter. Each of the testis is covered by a fibrous capsule called the tunica albuginea and it is further divided by partition of fibrous tissue from the tunica albuginea into 200 - 400 wedge-shaped lobes or sections. In each lobe there are 3 -10 coiled tubules known as seminiferous tubules, its function is to produce the sperm cells. The partition between both lobes and the seminiferous tubules converges in one area, near the anal side of each testis to form mediastinum testis.
Testes have the germ cells, which is differentiated into mature spermatozoa, Sertoli cells (they are the supporting cell), and Leydig (intestinal) cells (they are also known as testosterone-producing cells). The germ cell migrates to the fetal testes from the embryonic yolk sac, Sertoli cell is interspersed between the germinal epithelial cells within the seminiferous tubule, they are analogous to the granulosa cells in the ovary. The Leydig cell is located beneath the tunica albuginea, in the septal walls and between the tubules are analogous to the hormone-secreting interstitial cells of the ovary. The shape of Leydig cells are irregular and they commonly have more than one nucleus. These Leydig cells frequently contain fat droplets, pigment granules and the crystalline structure. These cells vary greatly in numbers and appearance among the various animal species and they are surrounded by blood, lymphatic vessels, and as well as by nerve fibres.
In primitive times the embryonic differentiation of indifferent gonads into either testes or the ovaries would be determined by the presence or absence of genes carried on the y chromosome.
Spermatogenesis
The seminiferous tubule is one, where the sperms are produced and it constitutes about 90 percent of the testicular mass. In young male humans, the tubules are simple and composed of undeveloped sperm-producing cells called spermatogonia and the Sertoli cells. Once the young males grow the tubules become branched and spermatogonia are changed into fertile sperm cells and after a series of transformation, it is called spermatogenesis. Sertoli cells are present in both the young and matured males to support mechanically and protect the spermatogonia.
The spermatogonia in the tubules get matured into spermatocytes, further, it matures into spermatids and that matures into spermatozoa as they move into the central lumen of the seminiferous tubule. Spermatozoa are stored in the seminal vesicle moving through the epididymis and the spermatic duct for eventual ejaculation with the seminal fluid.
Torsioned Testicles
It is the condition of the testicular torsion, in which twisting of the spermatic cord takes place and it brings blood down to the scrotum. Due to the condition of twisted testicles, the reduced blood flow causes sudden often pain and swelling. This is most common in males of age 12 - 18, but it can occur at any stage of life.
In this condition, it requires emergency surgery, if treated on time testicles can be saved. For any reason, if blood flow is cut for too long, the testicle might become so badly damaged that it might have to be removed.
Interesting Facts About Testicles
Human testicles means testes produce nearly around 200 million sperms a day.
In real testis of human are not the same, one of the testis is always smaller when compared with the other one.
The human testicle is the organ in the human body, which contains more diverse protein than any other organ in the body.
FAQs on Testis Anatomy and Role in Male Reproductive System
1. What is the testis in biology?
The testis is the male reproductive organ responsible for producing sperm cells and the hormone testosterone. It is one of a pair of oval-shaped glands located inside the scrotum in human males.
- Produces male gametes through spermatogenesis
- Secretes male sex hormones (androgens), mainly testosterone
- Essential for male fertility and secondary sexual characteristics
2. What is the function of the testis?
The main function of the testis is to produce sperm and secrete testosterone. These functions are vital for reproduction and male development.
- Sperm production: Occurs in the seminiferous tubules
- Hormone secretion: Leydig cells produce testosterone
- Supports development of male reproductive organs and secondary sexual traits
3. Where are the testes located in the human body?
The testes are located in the scrotum, a skin sac outside the abdominal cavity. This external position helps maintain a temperature slightly lower than body temperature, which is necessary for sperm production.
- Positioned below the penis
- Kept 2–3°C cooler than core body temperature
- Temperature regulation supports efficient spermatogenesis
4. What is the structure of the testis?
The testis is composed of tightly coiled seminiferous tubules enclosed within protective layers. Its internal structure is specialized for sperm production and hormone secretion.
- Seminiferous tubules: Site of sperm formation
- Sertoli cells: Support and nourish developing sperm
- Leydig cells: Located between tubules and produce testosterone
- Covered by a fibrous capsule called tunica albuginea
5. How does spermatogenesis occur in the testis?
Spermatogenesis is the process by which sperm cells are formed in the seminiferous tubules of the testis. It involves a series of mitotic and meiotic divisions.
- Spermatogonia divide by mitosis
- Form primary spermatocytes that undergo meiosis I
- Produce secondary spermatocytes and then spermatids via meiosis II
- Spermatids differentiate into mature spermatozoa
6. What is the difference between Sertoli cells and Leydig cells?
The key difference is that Sertoli cells support sperm development, while Leydig cells produce testosterone. Both cell types are essential for normal testicular function.
- Sertoli cells: Located inside seminiferous tubules; nourish and regulate developing sperm
- Leydig cells: Found between tubules; secrete testosterone
- Together regulate male fertility and hormonal balance
7. Why are the testes located outside the abdominal cavity?
The testes are located outside the abdominal cavity to maintain a lower temperature required for effective spermatogenesis. Sperm production is temperature-sensitive and functions best slightly below core body temperature.
- Scrotal temperature is about 2–3°C lower than body temperature
- High temperature can reduce sperm count and quality
- Cremaster and dartos muscles help regulate testicular temperature
8. What hormone is produced by the testis?
The primary hormone produced by the testis is testosterone, a major male sex hormone. It is secreted by the Leydig cells.
- Stimulates sperm production
- Promotes development of male reproductive organs
- Responsible for secondary sexual characteristics such as deep voice and facial hair
9. What is the difference between testes and ovaries?
The testes are male gonads that produce sperm and testosterone, while the ovaries are female gonads that produce eggs and estrogen. Both are reproductive glands but differ in structure and function.
- Testes: Produce sperm and testosterone
- Ovaries: Produce ova (eggs) and estrogen/progesterone
- Testes are located in the scrotum; ovaries are located inside the pelvic cavity
10. What happens if the testes do not function properly?
If the testes do not function properly, it can lead to infertility and hormonal imbalances. This condition may affect sperm production or testosterone levels.
- Low sperm count or poor sperm quality
- Reduced testosterone causing delayed puberty or reduced secondary sexual traits
- Possible causes include injury, genetic disorders, or hormonal dysfunction
